Biological Psychology Biological Roots of Behavior How the Brain Governs Behavior Neurotransmitters.
SURVEY OF MODERN PSYCHOLOGY The Brain. We will discuss: The parts of the brain and what they do ...
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Transcript of SURVEY OF MODERN PSYCHOLOGY The Brain. We will discuss: The parts of the brain and what they do ...
SURVEY OF MODERN PSYCHOLOGY
The Brain
We will discuss:
The parts of the brain and what they do Neurotransmitters The effects of various drugs on the brain
and neurotransmitters
Some general notes about the brain Bilaterally symmetrical along the
longitudinal fissure The left and right side communicate
via the corpus callosum Contra lateral control – the left side
of the brain controls the right side of the body and vice versa
The parts of the brain
Going from the back of the brain towards the front, functions are more advanced
Hindbrain Midbrain Forebrain
Hindbrain
Hindbrain
Cerebellum Balance
Damage (permanent or chemical) causes a wide staggering gait Performance and timing of skilled movements
Damage here causes tremors during movement and an inability to perform rapidly alternating movements
Ex. This would interfere with a skill such as typing Pons
Regulating the brain’s level of attentiveness Initiating sleep and dreaming Integrates movements of and sensations from the facial muscles,
eyes, tongue, and ears Medulla
Controls basic biological functions Cardiovascular and respiratory systems Reflexes (e.g. coughing, swallowing, sneezing) Maintains balance by controlling head orientation and limb
positions with respect to gravity)
Midbrain (Mesencephalon)
Midbrain (Mesencephalon)
•Includes the Tectum and Tegmentum•Tracking moving stimuli (visual and auditory)•Controls eye movements•Coordinates simple movements (controlled by the hindbrain) to form more complicated wholes•Damage here makes the organism unable to perform purposeful behaviors
•E.g., an animal can move and chew, but will not initiate a search for food when it is starving
Forebrain
Forebrain
Parts: Cerebral cortex Limbic system Thalamus Hypothalamus
Forebrain Thalamus
Receives sensory information and conveys it to the relevant structures E.g., vision and other senses, balancing information for movement
Hypothalamus Controls the autonomic nervous system, endocrine system, and major biological
drives
Basal ganglia Control of movement Damage/degeneration here causes Parkinson’s disease
Weakness, tremors, rigidity of limbs, poor balance, difficulty in initiating movements
Includes the hippocampus and amygdala Learning Memory Storing new information into long term memory Some regions are involved in emotions – feeling and expressing emotion,
emotional memories, and recognition of signs of other people’s emotions Stimulation generally produces feelings of anxiety and/or rage
Cerebral Cortex
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Cerebral Cortex
Frontal lobe Memory, strategy formation, response inhibition Conscious thought
Parietal lobe Senses (touch, pain, temperature)
Temporal lobe Hearing
Occipital lobe Vision
The frontal lobe is largely linked to personality
Much of what we know comes from instances of brain damage or injury
Phineas GageIn an accident in the mid 1800s, a large
steel rod went through his headHe survived, but friends said that there
were major changes in his personality and was “no longer Gage”
In general, injury to the frontal lobe results in: Lack of spontaneity Few facial expressions and gestures Limited and non-fluent speech Strategy formation Lack of response inhibition
The person does not understand rules and therefore has difficulty following rules
•The Hemispheres
•There is a lot of popular theory/cultural belief that the left and right hemispheres serve vastly different functions. •In reality, both hemispheres do play some part in almost all areas.•Most likely, one side is simply more effective and efficient in performing specific tasks.•The division of labor is described as seen in right handed people.
Visual System
Auditory System
Left Hemisphere Language related
sounds
Right Hemisphere• Non-language,
environmental sounds
• Music
Somatosensory System
Left Hemisphere Unknown
Right Hemisphere• Tactile
recognition of complex patterns• E.g., Braille
Movement
Left Hemisphere Complex voluntary
movement
Right Hemisphere• Movements in
spatial patterns
Memory
Left Hemisphere Verbal memory
Right Hemisphere• Nonverbal
memory
Language
Left Hemisphere Speech Reading Writing Arithmetic
Right Hemisphere• Prosody • Narrative• Inference
Spatial Processes
Left Hemisphere Unknown
Right Hemisphere• Geometry• Sense of
direction• Mental rotation
of shapes
Final Notes on Hemispheres
The left and right hemispheres are joined by the corpus callosum.In some severe cases of epilepsy, surgery is performed to cut the corpus callosum.
1981: the Nobel Prize was given to Roger Sperry for his research on “split brains”A participant was prevented from seeing the object and given a pencil in their left hand
The nerve impulse therefore reached the right hemisphere, but not the leftThe participant could generally demonstrate what the pencil should be used for with motions, but could not name the objectThey could only name the object if it was placed in the right hand.
When shown a stimulus is shown on the right side (processed by the left hemisphere) such as words, it is processed faster than if the same was shown on the left side. The right hemisphere needs to send the image to the left side for processing.
Brain Damage
Apraxia Disturbances in movement Lesions in the frontal lobe; disconnect in
primary and nonprimary motor areas Disturbances in initiation or organization of
voluntary actions Ex. Unable to wave Ex. When trying to bake, a person might try to
repeatedly break the same egg, or put a measuring spoon in a bowl as well as the ingredient
Brain Damage
Agnosia Inability to identify familiar objects using a
particular sense Visual agnosia – able to identify a car key by
touch, but not by appearance Able to recognize parts but not a whole
Prosopognosia – inability to identify faces This might be the inability to recognize a
face as a face
Brain Damage
Aphasia Disturbances in language Caused by damage by lesions, usually in the left
hemisphere Nonfluent aphasia
Inability to produce speech, but comprehending what is said Fluent aphasia
Inability to comprehend what is said Speech is made of filler words, with no information
People who can hear sometimes learn Sign Language to communicate
HOWEVERDeaf people who suffer the same brain damage
experience the same difficulties in communication as hearing people with aphasia
Neurons
Parts of a neuron: Dendrites
Receive impulses from other neurons
Cell body Axon Synapse (the space between
cells)
Communication occurs across synapses via neurotransmitters Neurotransmitters are usually
ejected, brought back into axons, and then reused
Lock and key model: the transmitter will only have an effect if it fits into the receptor molecules
Neurotransmitters
The ones we will discuss are: Dopamine Serotonin Norepinephrine Acetylcholine GABA Glutamate Endorphins
Dopamine
Normal function Produces sensations of pleasure and reward Used by the central nervous system (CNS)
neurons involved in voluntary movement Problems associated with imbalance
Schizophrenia Parkinson’s disease
Substances that affect the action of this neurotransmitter Cocaine Amphetamine Alcohol
Serotonin
Normal function Regulates sleep and dreaming, mood, pain,
aggression, appetite, and sexual behavior Problems associated with imbalance
Depression Some anxiety disorders Obsessive compulsive disorder
Substances that affect the action of this neurotransmitter Hallucinogenics
Norepinephrine
Normal function Used by neurons in the automatic nervous system
and by neurons in almost every region of the brain Controls heart rate, sleep, stress, sexual
responsiveness, vigilance, and appetite Problems associated with imbalance
High blood pressure Depression
Substances that affect the action of this neurotransmitter Tricyclic antidepressants Beta blockers
Acetylcholine
Normal function The primary neurotransmitter used by neurons
carrying messages form the CNS Involved in some kinds of learning and memory
Problems associated with imbalance Some muscular disorders Alzheimer’s disease
Substances that affect the action of this neurotransmitter Nicotine Black widow spider venom Botulism toxin
GABA
Normal function The most prevalent inhibitory neurotransmitter
in neurons of the CNS Problems associated with imbalance
Anxiety Epilepsy
Substances that affect the action of this neurotransmitter Barbiturates “Minor” tranquilizers (ex. valium) Alcohol
Glutamate
Normal function The primary excitatory neurotransmitter in
the CNS Involved in learning and memory
Problems associated with imbalance Release of excessive glutamate causes brain
damage after strokes Substances that affect the action of this
neurotransmitter PCP (angel dust)
Endorphins
Normal function Pleasurable sensations Control of pain
Problems associated with imbalance Lowered levels resulting from opiate addiction
Substances that affect the action of this neurotransmitter Opiates (opium, heroin, morphine, methadone)
Drugs
Drugs act on synapses (the spaces between neurons) and affect the response to neurotransmitters
Agonists facilitate effects Antagonists inhibit effects Dependence and addiction are
characterized by tolerance and withdrawal
Drugs
Physical vs. psychological dependence Physical addiction is often defined by the
physiological effects that happen when a person stops using a drug
Psychological dependence involves the emotional feeling of wanting the drug either to produce pleasure or avoid discomfort Psychological addiction tends to be more difficult to
overcome than physical addiction
Positive reinforcement – if it feels good, keep doing it! Withdrawal is the opposite of whatever the effects of
the drug are (E.g., withdrawal from an opiate causes agitation)
Types of Drugs and their Effects Opiates Stimulants Nicotine Alcohol and Barbiturates Cannabis/THC
Opiates
Naturally occurring opiates in the brain block pain
Cause analgesia, hypothermia, sedation, reinforcement
Act on GABA and dopamine Opiate blockers may be used to treat
addiction (no effect, therefore no reinforcement)
Stimulants
Dopamine agonists Stimulate the release of dopamine and
inhibit the reuptake Euphoric, active, and talkative
Hallucinations, paranoia, mood disturbances, repetitive behavior
Similar to schizophrenia
Nicotine
Dopamine and acetylcholine agonists Often harder to quit than “hard” drugs Withdrawal includes anxiety,
restlessness, insomnia, inability to concentrate
Nicotine antagonists can also reduce cocaine cravings
Alcohol and Barbiturates
Dopamine and GABA agonists Small doses produce mild euphoria and inhibits anxiety –
stops the punishing effects of aversive stimuli Ex. if an animal is given shocks when it performs a particular
action, it will stop. If given alcohol, it will not learn and keeps performing the response
Alcohol: Withdrawal can be fatal
Convulsions and seizures Chronic alcoholism can lead to Korsakoff’s Syndrome
This is caused by a vitamin deficiency – frequent alcohol use can block the absorption of some vitamins
Permanent anterograde amnesia (inability to form new memories, but still having old ones)
Confabulation – making up memories Can have elements of reality or be completely imaginary
Cannabis/THC
Cannabis: Dopamine agonist Particularly affects the hippocampus,
causing memory problems Long term use can cause inattentiveness,
impaired memory, reduced ability to multitask